Motor-driven sewing machine



March 6, 1928. 1,661,824 M. HEMLEB MOTOR DRIVEN SEWING MACHINE Filed May 19. 1925 O in INVENTOR SUPPLY BY v ATTORNEY Patented Mar. 6, 1928.

UNITED STATES PATENT OFFICE.

MARTIN HEMLEB, OF ELIZABETH, NEW JERSEY, ASSIGNOR TO THE SINGER mo- FACTURING COMPANY, OF ELIZABETH, NEW JERSEY, A CORPORATION OI NEW JERSEY.

MOTOR-DRIVEN SEWING MACHINE.

Application filed May 19, 1925.

This invention relates to motor driven sewing machines and more particularly to sewing machines of the type having a small individual driving motor mounted on the sewing machine frame and connected directly to the sewing machine balance-wheel. The motor of such an outfit is customarily of the series wound type and is controlled through a treadleor knee-operated rheostat connected in series with the motor. Motors of the high-speed type are customarily used for this work to gain the necessary power to drive the machine in a motor of small size and weight; light weight and ready portability of the outfit being an important desideratum.

Heretofore the motor-shaft has been fitted with a small pulley which has been connected to a larger pulley on the sewing ma-' chine balance-wheel, thereby effecting the necessary speed reduction to drive the machine at normal speed.

An undesirable characteristic of an outfit such as above described is that the motor will not run steadily at low speeds or when the rheostat is shifted to include considerable resistance in the motor circuit. For certain classes of work with sewing machines, such as embroidering, it is essential that the machine run steadily at a very low speed so that the operator can shift the work between stitches and have time to accurately position the work for each needle-thrust. The unsteady running characteristics of the above described prior motor-driven sewing machines at low speeds is found to be due very largely to the bearing friction on the motorshaft caused by the side thrust on the small pulley of the motor. Further, in a beltdriven outfit, the sharp degree of flexing of the belt required when running over a small pulley increases the belt tension required to prevent slippage, and small variations in the load on the motor, such as caused by irregu larities in the belt, have considerable effect upon the speed of the motor, sometimes causing it to stop and then as the resistance of the controller is reduced, to jump ahead at too great a speed for embroidering.

The present invention has for an object to provide a sewing machine with a. motor attachment and motor controller whereby the machine may at the will of the operator- Serlal No. 31,284.

slippage is considerably reduced; the wrap of the belt around the driving pulley is increased and the speed of the motor and machine may be nicely controlled at both normal running and low speeds by means of the usual rheostat connected in series with the motor; a result not heretofore attained in a light weight motor-driven sewing machine outfit.

In the accompanying drawings illustrating a preferred embodiment of the invention, Fig. 1 is a rear end elevation of a sewing machine and motor driving device embodying the invention. Fig. 2 is a fragmentary horizontal section through the motor and sewing machine standard. Fig. 3 is a vertical section through the driving pulley. Fig. 4 is a perspective view of the motorframe. Fig. 5 is a perspective view of a guard or disk cap for the gear drive. Fig. 6 is a perspective view of the supporting stud for the driving pulley and Fig. 7 is a diagram of the electric circuit for the motor and controller.

The sewing machine comprises the usual bed 1 and bracket-arm standard 2 and mainshaft 3 carrying the usual balance-wheel 4 having the belt-groove 5. Secured to the seat 6 on the standard 2 by means of the screw 7 is the motor-bracket 8 having a slot 8 through which the screw 7 passes, such slot permitting a vertical shift or adjustment of the bracket 8 for belt-tightening purposes.

Secured to the bracket 8 by the screw 9 is the motor-frame 10 in which is journaled the motor-shaft 11, one end of which projects through the bearing aperture 12 in the m0- tor-frame and has fixed thereto the pinion 13.

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dournaled on the stud 14l fixed in the aperture 15 in the motor-frame between the motor-shaft 11 and the standard 2 is the relatively large driving pulley 16 which is cupped out to fit over the pinion 13 and is formed with an internal gear 17 meshing with the pinion 13. The driving pulley 16 is connected to the sewing machine balancewheel, such connection being preferably a belt 18 which is led around the pulleys 5 and 16, both of which are of comparatively large diameter and do not require the belt to 'l-lerr sharply.

A dust-guard 19 having a clearance aperture 20 for the motor-shaft is secured to the motor-frame by means of the stud 14 which passes through the aperture 20 in the dusgguaro and has a collar 21 between its ends for holding the guard 19 to the motor-trains. The stud let is hollow, Fig. 3, and is pro vided with an internal wick 22 for con ducting lubricant from the oil-cup 23 to the bearingfor the pulley 16.

The motor is of the usual series wound type as indicated in Fig. 7 and is connected in series with the usual treadle or knee-operated rheostat.

By use of the present construction the machine may be operated at the usual running speeds and may also be nicely cont-rolled at low speeds such as required for embroidering. The motor is of the light weight high-speed type controlled by the usual rheostat and hence use of the present groveinent entails no sacrifice oi the de menses sirable characteristics of prior sewing ma chine motor drives.

The bracket 8 is preferably constructed substantially in accordance with the disclosure of my Patent No. 1,520,9t9, dated December 30, 1924. v

It will be seen that the comparatively large pulley 16, being journaled between the vertical plane of the motor-shaft 11 and sewing machine standard 2, does not extend rearwardly beyond the motor-frame or rearward edge of the bed 1 and thus does not interfere With the housing of the machine under the cover of the usual carrying case or in the usual drop-head cabinet.

Having thus set forth the nature of the invention, what I claim herein is In a motor driving attachment for sewing machines, the combination with an electric motor having a frame and motor-shaft, said trams having a shaft bearing aperture and a stud-pin aperture spaced from said shaft bearing aperture, of a stud-pin secured in said stud-pin aperture and "formed with a collar between its ends, a driving pulley journaled on said stud-pin and having an in- V ternal gear, a pinion fixed to the motor-shaft and meshing with said internal gear, and a dust cap secured to the motor-frame by the collar on said stud-pin and covering said internal gear and pinion.

in testimony whereof, l have signed my name to this specification.

Maurie uni/inns. 

